In an exciting step forward for justice and common sense, NYPD Commissioner Ray Kelly has issued a directive ordering officers to stop arresting people for misdemeanor marijuana possession when the pot only becomes "public" because an officer has searched a person or directed the person to empty his or her pockets.

In New York, possessing a small amount of marijuana is not a crime unless it is in public view. If you're caught with a little pot in your pocket or bag, you can be ticketed and fined, but not arrested. Yet, according to researchers, over the past several years NYPD officers have wrongfully arrested hundreds of thousands of New Yorkers on misdemeanor marijuana possession charges after coercing or tricking them into revealing small amounts of pot they had concealed in their pockets or bags.

This end-run around state law has been a primary tactic in NYPD's decade-long marijuana arrest crusade. It's a grave injustice that hurts people and families, and cost taxpayers $75 million last year. Marijuana arrests lead to a host of negative consequences, including a permanent criminal record, loss of student financial aid or deportation.

In issuing his directive, he implicitly recognizes that NYPD officers have been going too far. This comes as no surprise to the more than 350,000 people — overwhelmingly black and Latino — who have been wrongly arrested for misdemeanor marijuana possession in New York City since 2002 — more than 100,000 in the past two years alone.

While the new directive is an important step forward, it will have little impact unless the NYPD vigilantly enforces it. It must commit resources to training officers to comply with the law, and to monitor compliance by regularly collecting and reviewing arrest data and police reports, as well as communicating openly and directly on this issue with the communities that bear the brunt of the city's policing strategies. If there is a real commitment from the Police Department to enforce Commissioner Kelly's directive, we should see a substantial decline in the number of marijuana arrests. Of course, we'll keep our eyes peeled, and if unconstitutional charges and arrests continue, Commissioner Kelly will hear about it.